1. Field of the Invention
The present invention relates to the security device for preventing an information storage media like DVD, CD and video tape from pilferage, and more specifically to the security devices which has locking function and the locking status can only be released by a decoupler.
2. Description of the Prior Art
The information storage media like DVD, CD are displayed in the retail store or rental store contained in a case. Because of the small size of the information storage media, pilferage is occurring frequently. Recently, security devices, equipped with locking function that can only be released by the decoupler installed at the counter, are widely used.
U.S. Pat. No. 5,598,728, U.S. Pat No. 5,850,752 and U.S. Pat. No. 5,988,376 disclose the above said prior arts.
In FIG. 1 through FIG. 3 are shown the prior art as disclosed in above patents.
As shown in FIG. 1, the prior art of security device includes a case 100 for receiving merchandise, and locking mechanism 200 for latching the case closed. The case 100 has a notch 110, 120 at the lower portion of both sides. The locking mechanism 200 is comprised of a housing 230 with a flange 232 which covers the lower part of case 100; a fixed hook 210 which is installed at one end of the housing; and a movable hook 220 which is movably installed at the other end of the housing 230. The locking operation is as follows: the fixed hook 210 is inserted in the notch 120 provided at one side of the case 100, and then the movable hook 220 moves to the locking position thus being inserted into the other notch 120 on the other side of the case 100.
As shown in FIG. 2, the movable hook 220 has a extended member 222 which is extended toward the inner part of the housing 230. A cross piece 224 with a curved segment 224a at the center portion is provided under the extended member 222. A pair of opposing sleeves 240 are formed on the inner wall of the housing 230. Each sleeve 240 has a steel pin 242 which contacts the cross piece 224 and supported by a spring 241 installed in the sleeve. The movable hook 220 moves to locking location and fixed in that location by the steel pin 242 which exerts force from the spring 241 on the both sides of the cross piece 224. Meanwhile, a front surface 223 of the extended member 222 is supported by an additional spring 250. When the steel pin 242 is released from the cross piece 224, spring pushes back the movable hook 220 to the releasing position located outside of the housing 230 thus releasing the movable hook 220 from the notch 120 of the case 100.
As shown in FIG. 3, the releasing operation of the movable hook 220 is made by a decoupler 300. The decoupler 300 is equipped with two opposing magnets 310 spaced at a distance slightly larger than the width of the housing 230. When the housing 230 locates between two magnets 310, the magnets 310 attract the steel pin 242 apart from the cross piece 224, while compressing the spring 241. Then, the spring 250 pushes back the movable hook 220 to previous releasing position thus releasing the locking condition of the case 100.
However, the prior arts, like the security device mentioned above, has the problem of weak locking force as the prior arts employ the locking mechanism which is fixed to a locking position by the spring 241 which pushes the steel pin 242 against the side surface of the cross piece 224.
In addition, the prior art of security device has a defect of complex releasing operation process, as one has to hold the locking mechanism 200 with on hand and lift up the case 100 with the other hand, thus entailing the use of both hands.